Method of making coaxial cables



Feb. 28, 1967 R. Y. GILL ETAL METHOD OF MAKING COAXIAL CABLES 2 Sheets-Sheet 1 Filed Feb. 7, 1964 Inventors RON/440 Y. 67!. L GER/l4 By% 0 AJVOREL Feb. 28, 1967 R. Y. GILL ETAL METHOD OF MAKING COAXIAL CABLES 2 Sheets-Sheet 2 Filed Feb. 7, 1964 mo m M w w Lm n A w 0 rm M w N A) 0 m R 6 y United States Patent 3,306,793 METHOD OF MAKING COAXIAL CABLES Ronald Yaxley Gill and Gerald Alan Morel, both of London, England, assignors to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Feb. 7, 1964, Ser. No. 343,240 Claims priority, application Great Britain, Mar. 15, 1963, 10,367/63 3 Claims. (Cl. 156-54) This invention relates to coaxial cables.

According to the present invention there is provided a coaxial cable which includes an inner conductor, an outer conductor and a tube of electrical insulating material supporting the outer conductor and composed of at least one folded strip provided with projections which support the inner conductor.

Further according to the present invention there is provided a method of manufacturing a coaxial cable which includes the steps forming projections on a strip of electrical insulating material; folding the strip round an inner conductor to form a tube with the projections supporting the inner conductor along the centre of the tube and applying an outer tubular conductor to the outer surface of the tube.

In the accompanying drawings which, by way of example, illustrate diagrammatically embodiments of the present invention:

FIG. 1 is a perspective view of a strip of polythene;

FIG. 2 is an end view in the direction of arrow X of FIG. 1;

FIG. 3 is a perspective view of a coaxial cable cut away to reveal the strip shown in FIGS. 1 and 2;

FIG. 4 is an end view of an alternative polythene strip to that shown in FIG. 1;

FIG. 5 is a perspective view of a polythene strip;

FIG. 6 is a perspective view of a coaxial cable cut away to reveal the strip shown in FIG. 5;

FIG. 7 is a perspective view of a polythene strip; and

FIG. 8 is a partly sectioned side view of a coaxial cable including the strip shown in FIG. 6.

Referring to FIGS. 1, 2 and 3 a polythene strip 1 is provided with projections 2. In the end view (FIG. 2) the projections 2 have the shape of isosceles triangles with angle A equal to 120. The sides 3 and 4 of the strip 1 are in the same plane as the sides of the projections adjacent to them.

In FIG. 3 the strip 1 is shown longitudinally folded round an inner conductor 5 so that the projections 2 form discs 7 spaced along it and the whole is enclosed in an outer conductor 6.

The strip 1 with the projections 2 may be produced in any known manner from a preformed strip, for example, by passing a preformed polythene strip between heated forming rollers or by vacuum forming. When the strip 1 has been formed with the projections 2 it is longitudinally folded round an inner conductor 5 which is being unreeled from a supply drum. An outer conductor 6 is then folded round the strip 1 by, for example, longitudinally folding a copper strip round the strip 1 with its longitudinal edges diametrically opposite those of the strip 1. The whole may then be screened with a helically or longitudinally applied steel tape to constitute a coaxial cable core of a single or multi-core cable.

If desired the strip 1 may be wound helically upon the inner conductor 1 and the bands of projections 2 arranged at a suitable angle across the strip 1 to form the discs 7.

The strip 1 may be divided longitudinally into a num- Referring to FIG. 4 there is shown an alternative polythene strip 8 provided with projections 9 which are the same shape as the projections 2 (FIG. 2). The strip 8 is curved at the base of the projections 9 to the same curvature that the strip 8 takes when it is folded round the inner conductor 5 (FIG. 3). .By curving the strip 8 in this manner the tendency of the strip 8 to form flats at these places when it is folded round the inner conductor 5 is avoided.

Referring to FIGS. 5 and 6 the provided with alternate bands 11 and 12 of projections. The projections 13 on the band 11 are the same as the projections 2 (FIG. 2). The intermediate projections 14 on the band 12 are the same as the projections 2 (FIG. 2) whilst the end projections 15 together form a projection 2 (FIG. 2) when the strip 10 is folded round an inner conductor 16.

When the strip 10 is folded round the inner conductor 16 the meeting edges of the projections 13 are angularly displaced from the meeting edges of the projections 14. In this manner the projections 13 and 14 tend to hold the inner conductor 16 more rigidly in a central position. An outer conductor 17 is placed round the folded strip 10 in the same manner as in FIG. 2.

Refer-ring to FIGS. 7 and 8 there is shown a polythene strip 18 provided with bands 19 of projections 20 which cross the strip 18 at an angle. The bands 19 are so polythene strip 10 is arranged that when the strip 218 is longitudinally folded her of strips which are placed side by side round the in- 7 ner conductor 5.

round an inner conductor 21 the projections 20 form a continuous 'helix 22 round it. An outer conductor 23 is provided in the same manner as in FIG. 2.

A continuous helix 22 could also be provided by providing a strip 20 with a longitudinal band of projections 20 and winding the strip 20 about the conductor 21 in a helical manner.

In either case a number of parallel helices 22 may be provided by suitably sloping the bands 19 across the strip 18 when it is longitudinally folded round the inner conductor 21 or by providing a number of longitudinal bands 19 along the strip 18 when the strip 18 is applied helically to the inner conductor 21.

By forming the projections on the polythene strip on the top of a heated metal strip which is to form the outer conductor these two members may be bonded together and applied to the inner conductor in one operation.

It is to be understood that the following description of specific examples of this invention is not to be considered as a limitation on its scope.

What we claim is:

1. A method of manufacturing a coaxial cable comprising a continuous longitudinal strip of electrical insulating material which includes the steps of:

forming on a continuous longitudinal strip of electrical insulating material groups of relatively thin contiguous triangulated projections of the same insulating material joined at their base and arrayed thereon transverse to the longitudinal axis thereof;

folding said strip longitudinally about an inner conductor to form a continuous tube so that said projections extend inwardly therefrom and the edges of adjacent projections meet to surround and support said inner conductor centrally and form a plurality of supports at spaced intervals along the length thereof; and

applying an outer tubular conductor to the outer surface of said tube.

2. A method as claimed in claim 1 including forming groups of said projections at right angles across said strip to form dis-c supports when folded round said inner conductor at spaced intervals along its length.

3. A method as claimed in claim 1 including forming 3 4 said projections diagonally across said strip to form a 2,897,542 8/ 1959 Isenberg. I helical support. 3,117,902 1/1964 Holz'heinier 1 l56217 References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 5 428,390 6/ 1911 France- 1,939,264 12/1933 Hill 17429 X 2,269,991 1/1942 Soheldorf 174-28 x LEWIS MYERS W 2,330,381 9/ 1943 Quayle l74--28 J. F. BURNS, D. A. KETTLESTRING'S, H. HUBER- 2;643,327 6/ 1953 Macklenar 174-28 X FELD, Assistant Examiners.

2,890,739 6/1959 Haines 1562l8 X 10 

1. A METHOD OF MANUFACTURING A COMPRISING A CONTINUOUS LONGITUDINAL STRIP OF ELECTRICAL INSULATING MATERIAL WHICH INCLUDES THE STEPS OF: FORMING ON A CONTINUOUS LONGITUDINAL STRIP OF ELECTRICAL INSULATING MATERIAL GROUPS OF RELATIVELY THIN CONTIGUOUS TRIANGULATED PROJECTIONS OF THE SAME INSULATING MATERIAL JOINED AST THEIR BASE AND ARRAYED THEREON TRANSVERSE TO THE LONGITUDINAL AXIS THEREOF; FOLDING SAID STRIP LONGITUDINALLY ABOUT AN INNER CONDUCTOR TO FORM A CONTINUOUS TUBE SO THAT SAID PROJECTIONS EXTEND INWARDLY THEREFROM AND THE EDGES OF ADJACENT PROJECTIONS MEET TO SURROUND THE SUPPORT 